Hygrostat



Sept. 12, 1933. R. MILLIER 1,926,730

HYGROSTAT Filed Oct. 30, 1930 2 Sheets-Sheet l INVENTOR ATTORN EY'S R. MILLER Sept. 12, 1933.

HYGROSTAT Filed Oct. 30, 1930 2 Sheets-Sheet 2 I W 7 Z?! l a L mwmg m 7 E 3 MW @5 Patented Sept. 12, 1933 PATENT OFFICE.

nYGao s'ra'r Rudolph Miller, Detroit, Mich, asslgnor, by meme assignments,

to Edward .Mleh.

c. Lamleln, Detroit,

Application mm :0, 1930. Serial No. 492,185

4 Claims. (01. 297-1) This invention concerns automatic controls, and relates more particularly to hygrostats, or mechanisms adapted to be responsive to variations in the moisture content of the surrounding 6 atmosphere, and which include an electrical switch arranged to be automatically thrown, to close or open an electric circuit when the humidity of the air falls below or rises above certain desired levels.

An important object of this invention is the provision of such a hygrostatic controlling device which will be extremely simple and compact, but which nevertheless will produce mechanical action in response to the required hu- 15 midity changes which is of sufiicient extent and force to directly actuate a controlling switch carrying a relatively heavy current, as for a suitable humidifying device, eliminating the neces sity of an interposed, relay.

Another object of this inventionis the provision of such a device which will be of unprec edented sensitivity and quickness in responding to humidity variations.

A further object of this invention is the provision of a novel and highly efficient controlling element for such a device which is productive of greater and more positive mechanical movement for its size than any heretofore developed,

and which is of such form as to render its entire surface effective.

Other objects and advantages will be apparent from the following description, wherein reference is made to the accompanying draw-v Figure 1 is a perspective view of my improved hygrostat with the cover in place, assembled and ready for operation, as it appears when mounted upon a wall or wherever desired, bringing out its symmetrical and pleasing appearance.

Figure 2 is a front elevational view of the hygrostat with the cover removed.

Figure 3 is a front elevational view of my device with boththe cover and the controlling. element removed. Figure 4 is a vertical sectional view taken substantially on the line 4-40! Figure 3. Figure 5 is a. sectional view taken substantially. on the line 5-5 of Figure 4.

Figure 8 is a sectional view taken substantial- 1y on the line e-s of Figure 4.

Figure l is a sectional view taken substantially on the line '7'l of Figure 4.

Referring now to the drawings:

Reference character 10 indicates a supporting back plate for my device, which may conveniently be cast from a suitable metal, as aluminum or an alloy thereof, and integrally with which certain of the supporting members may well be cast. The supporting members for the controlling element comprise the upstanding rigid posts 11, 12, l3, 14 which extend forwardly from the back plate, and carry tapped apertures at their ends, into which the machine screws l5. 16, 17, and 18 maybe screwed.

The controlling element comprises a thin baseless wooden cone or conical disk 20 (Figures 2, 4, and 5) the outer edge of which is tightly se cured by a restricting metallic band 21, which prevents it from expanding outwardly. The cone may be formed of any desired angularity, depending upon the extent of movement which it is desired to have its apex produce, and other mechanical considerations. It is preferably out with. the grain of the wood coaxial with the ilnished cone, in order that the end of the grain may be exposed upon its two surfaces. As shown. the cone is preferably formed with a relatively thin wall, so that it is in reality little more than a conic surface. More strictly speaking, the controlling element of the preferred form herein disclosed is a frusto-conical surface, since it does not itself come quite to a point, but is truncated to receive the bushing 19. The formation of the ring 21, which constricts the cone when moisture tends to expand it, is clearly shown in Figure 4, preferably being grooved and tight-- 1y fitted about the edge of the cone, as there shown. It will be obvious that since the cone cannot expand outwardly at its base, moistureindu'ced expansion of the cone forces its apex outwardly along the line of its axis, increasing the altitude of the cone. Conversely, as the cone dries out, its apex moves inwardly and the cone tends to'flatten. It is this movement of the apex of the cone which is utilized to operate my device.

The controlling cone is mmmted upon the four posts 11, 12, 13, and 14 by clamping the restrict-- ing ring 21 beneath the heads of the machine screws 15, 16, 17, and 18, The ends of the posts 105 may be suitably cut away or notched to receive the ring, as at 22, 23, 24, and 25, the ring fitting accurately within the four ledges thus formed.

Enough of the center or apex of the cone is cut away to enable fitting the bushing 19 therein, 11 which bushing is interiorly threaded to receive the adjusting screw 28, by means of which movement. of the point of the cone is transmitted to a lever, as 27, against which its end bears, (Figure 4). The lever as herein shown, is pivoted adjacent one extremity upon a horizontal axis, as bymounting it within the yoke 28, rigidly supported from the back plate 10, between suitable bearings, as 29-30. The bearing 30 may be adjustable, as shown in Figure 3. The long arm of the lever 27 projects upwardly, and carries a cam surface 32 at its top which engages a roller 31 carried by the short arm of a bellcrank 34, also mounted to pivot about a horizontal axis, which, however, is perpendicular to the axis of the lever 27. In this embodiment of my invention, the cam surface is formed to force the roller, and consequently the short arm of the bellcrank, upwardly when the lever arm 27 moves toward the back plate, and to permit its descent when the lever arm 27 moves forwardly and away from the back plate. The short arm of the bellcrank, which is designated 34, projects outwardly almost horizontally, the longer arm 35 depends almost vertically. The supporting pivot pins which provide the bearings for the bellcrank may be carried by and engage with the support 38, which is also rigidly secured to the back plate. The bellcrank pivot pins are designated 37 and 38, the latter ,of the twobeing adjustable. It will be seen that cone bearings are used for both the bellcrank and the lever 27, and that the fixed pins (29-37) are carried by their respective levers, while the adjustable pins (3038) are =carried by their respective supports, although this construction is of course optional. Integral with the long lever arms 27 is' a shorter arm 57, projecting substantially horizontally toward the back plate. A tensile spring 68 connects the lever arm 5''! and the short arm of the bellcrank,

thereby constantly urging the long arm 27 forwardly away from the back plate, and simultaneously urging the short arm of the bellcrank downwardly upon the cam surface 32.

The movement directly induced by the cam 32 which is part of the lever 27 is multiplied by the bellcrank, the long arm of which is used to tilt the mercury switch 40 which controls the circuit which the device is desired to govern. The preferred shape of the long arm 35 of the bellcrank is best shown in Figure 3.

The mercury switch is of conventional construction, comprising a sealed glass tube, preferably containing an inert gas, a quantity of mercury, and a pair of spaced contacts adapted to be electricallyconnected by the mercury when the tube is tilted in one direction, and to be disconnected when it is tilted in another direction. The contacts are connected to terminals 4142, which are sealed in the glass in the tube, extending therethrough. Insulated flexible connectors 4546 are fastened to the terminals outside the tube, and run to binding posts or other suitable terminals for the deviceitself, 43-44..

To allow its being tilted about a horizontal axis in the manner necessary to throw it, the mercury switch is preferably suspended from the pivot pin 47, which is pointed at its ends and j'ournaled in the back plate and in 9. depending bearing arm 48 rigidly carried by the yoke member 28, at its end, as is best shown in Figm'e 4. An adjustable bearing 54 may be provided for tube and its retaining member, which latter is formed of a sheet metal strip 51, wrapped about the tube and secured to the arm, as by the screw 52. consequent tilting of the tube, is through the agency of the pin 50, or other suitable projection carried by the arm, with which the bifurcated end 53 of the long arm 35 of the bellcrank engages. To prevent their interference with the free rotatability of the switch, the pigtail" connectors 4546 may be wrapped loosely one or two revolutions about the pivot pin 47, as shown in Figures 3 and 4.

It will now be apparent that if the controlling cone shrinks, as by drying out, so that its apex moves inwardly, in a direction away from the back plate, suiliciently, the forward movement of the lever 27 and consequent downward movement of the short arm 34 of the bellcrank, both springinduced, will swing the long arm 35 of the bellcrank to the left, tilting the switch to the right or on position. When this occurs, if a humidifying device and a source of current (not shown) are properly connected to the switch, the humidiiler will be turned on, and will remain on until the reverse operation takes place. This occurs when the cone swells suiiiciently, due to the absorption of the proper amount of moisture, to force the end of the adjusting screw outwardly sufficiently to move the lever arm 27 back toward its initial position and throw the switch in the opposite direction, which will of course turn 01! the humidifier or humidifiers, any desired number of which may be controlled by a single control unit. To controllingly vary the point at which the tripping of the switch takes place, it is of course merely necessary to adjust the regulating screw 26.

I also may provide visible indication of the percentage of humidity contained in the air by provision of the indicating needle and its actuating mechanism, for cooperation with which the outside of the casing may be fitted with a suitable scale, as 81, Figure 1. The needle is formed as a continuation of the lever 83, to the end of which it is amxed. The lever 63 may be swung about a horizontal axis, which is furnished and positioned to receive the end of the lever arm 57, which is a portion of the lever 27. The short bifurcated lever 88 may be secured to the shaft 64 in any suitable manner, as by being amxed to or integral with the sleeve 85, which may be forced on the spindle to engage the same by friction. When the long lever arm moves about the axis 29-30, the short lever arm 57 is simultaneously moved up or down, and its end Actuation of the supporting arm 49, and

being in engagement with the slot in the lever 88,

it rotates the shaft 34, and so moves the needle 60 over the scale. The slot in the lever 88 is designated 88, and the construction of this partis shown in detail in Figure 7, the entire needleoperating mechanism is brought out best in Figures 4, 5, and 8. v

A suitable cover 70, for the device may be formed with open or grilled or screened sides, as shown in Figure 1, to allow free circulation of air around and againstthe controlling cone, and

a suitable aperture, as 71, may be formed to While it will be apparent'that the illustrated embodiment of my invention disclosed is well calculated to adequately fulfill the objects and ad- -vantages primarily stated, it is to be understood that the invention is susceptible to variation, modification and change within the spirit and scope of the subjoined claims.

I claim:

1. A controlling element for,humidity-respon-,

sive apparatus comprising a stifi dished member expansible and contractible under varying humidity conditions, and means for restricting out ber expansible and contractible under varying humidity conditions and having a conical surface, means for restricting outward expansion at the base thereof, and means for applying thrust resulting from movement of the apex caused by expansion and contraction thereof to move another member, comprising a combined adjusting and thrust transmitting screw threaded into and. projecting from the apex, and a multiplying lever system actuated by said screw.

4. In a hygroscopic device, a controlling element comprising a relatively flat and rigid member having a relatively thin portion and a substantially frusto-conical surface, said member being expansible and contractible under varying humidity conditions, means for restricting outward expansion thereof at the base, and means for applying thrust generated by expansion thereof in another direction to actuate desired apparatus, comprising a multiplying lever system, and a combined thrust-transmitting and adjusting screw threaded into and projecting from the apexand connected to a portion of the lever system.

RUDOLPH MILLER. 

